CN104167845A - Rotor iron core for embedded permanent magnet motor and method for designing rotor iron core - Google Patents

Abstract

Provided is a rotor iron core for an embedded permanent magnet motor. A plurality of permanent magnets are evenly arranged on the rotor iron core in an embedded mode in the circumferential direction. The rotor iron core is characterized in that the outer edge, corresponding to the permanent magnets, of the rotor iron core comprises a basal surface and an upper top surface; the basal surface is attached to the surfaces of the embedded permanent magnets; the upper top surface is opposite to a stator iron core of the motor, so that an air gap is formed; the contour line at the junction of the air gap and the upper top surface of the rotor iron core is a curve formed by stacking an arc cosine wave and a third harmonic function, and the specific shape of the curve is expressed as specified in the formula. The rotor iron core has the advantages that the shape of the outer edge of a new rotor iron core is obtained through an arc cosine function and the optimal third harmonic function, on the premise that torque pulsation of the motor is not increased, torque output is increased, and therefore the motor has the advantages of being high in power density, efficient, capable of saving energy and running smoothly, low in noise and the like.

Description

The rotor core that built-in permanent magnetic motor is used and method for designing thereof

Technical field

The present invention relates to a kind of rotor core, particularly a kind of method for designing of rotor core and this rotor core thereof for built-in permanent magnetic motor.

Background technology

The permanent magnet of built-in permanent magnetic motor is directly to embed in the rotor of motor, a kind of rotor of built-in permanent magnetic motor the rotor > > of a Chinese utility model patent < < built-in permanent magnetic motor that is ZL201320336256.0 as the existing patent No. in prior art discloses, it comprises the rotor core of sheet laminated structure, embeds the permanent magnet in rotor core; Between permanent magnet and rotor core, there is space, by encapsulating fixed permanent magnet in space.Because the rotor core of sheet laminated structure can hinder flowing of casting glue, therefore in described space, insert encapsulating pipe, to assist encapsulating; The surfaces externally and internally of encapsulating pipe is all very smooth, is provided with six through holes on sidewall, along encapsulating pipe length direction, is arranged on both sides.

Rotor core in above-mentioned patent is not processed through cutting the utmost point, and the Gas-gap Magnetic Field Resonance Wave content producing between rotor core and motor stator is high, thereby causes the cogging torque of motor, operation torque pulsation large.In order to reduce cogging torque and the operation torque pulsation of motor, built-in permanent magnetic motor as shown in Figure 2, the permanent magnet 3 of this motor " be embedded at rotor core 2 " in, can be to rotor core 2 " and electronics stator 1 " between air gap 4 " length carries out anticosine and cuts the utmost point and process; although the method can reduce cogging torque and the operation torque pulsation of motor; also reduced the average torque of motor, thereby reduced torque density, the operational efficiency of motor simultaneously.Therefore, need to make further improvement.

Summary of the invention

First technical problem to be solved by this invention is the rotor core that the high and built-in permanent magnetic motor that output torque pulsation is little of a kind of delivery efficiency of motor is provided for above-mentioned prior art present situation.

The present invention solves the technical scheme that above-mentioned first technical problem adopts: the rotor core that a kind of built-in permanent magnetic motor is used, described rotor core is embedded with a plurality of permanent magnets along circumferentially uniform, it is characterized in that: the outer rim of the described rotor core of corresponding each permanent magnet includes

Basal surface, the surface of this basal surface and built-in permanent magnetic body fits;

Upper end face, on this, the stator core of end face and described motor is relative and establish and form air gap, the outline line of the upper end face intersection of described air gap and described rotor core is the curve that anticosine ripple and triple-frequency harmonics function are formed by stacking, and the function that the concrete shape of this curve is represented by following formula (I) is determined:

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-a\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(I\right)$

Above-mentioned formula (I) adopts polar coordinate system, wherein, and the L in above-mentioned formula (1) _g(θ) be the utmost point footpath of any point M on the outline line of upper end face intersection of described air gap and rotor core, θ is the polar angle of any point M on the outline line of upper end face intersection of described air gap and rotor core; τ _pfor pole span; A is for injecting the amplitude of triple-frequency harmonics; L _gfor minimal air gap distance; L _gdfor pole span.

As further preferred, when a=1/6, the curvilinear function of described formula (I) is as follows:

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-\frac{1}{6}\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(\mathrm{II}\right)$

Now, the torque of motor output is maximum.

The present invention solves the technical scheme that above-mentioned second technical problem adopt: the method for designing of the rotor core that a kind of built-in permanent magnetic motor is used, is characterized in that: described method for designing includes following steps:

(1), set the amplitude a=1/6 of described triple-frequency harmonics function, the upper end face curve shape of described rotor core is by the function representation of following formula (II):

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-\frac{1}{6}\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(\mathrm{II}\right)$

(2), curve that function in described formula (II) is formed substitutes by three sections of camber lines that connect successively, described three sections of camber lines are respectively left half arc, top arc and right half arc, wherein left half arc and right half arc are for being symmetrical arranged;

(3), set the curve peak L that the function in described formula (II) forms _g(θ) _maxthe point tangent with the horizontal line that represents motor gas-gap is P1, sets the curve minimum point L that the function in described formula (II) forms _g(θ) _minfor P2;

(4), described top arc is radius and through the drawn circular arc of described some P1, some P2, determines respectively by take the maximum radius of described rotor core;

(5), described left half arc is by determining through described some P1, P2 and with the tangent circular arc of the horizontal line of described motor gas-gap respectively, described right half arc is symmetrical arranged with described left half arc and arc radius equates;

(6), described left half arc, top arc be connected successively with right half arc, formed camber line is the upper end face contour curve of described rotor core.

In order to facilitate curved face processing, as preferably, between described left half arc, top arc and right half arc, be smooth transition connection.

Compared with prior art, the invention has the advantages that: by an inverse cosine function, add the outer rim shape that optimum triple-frequency harmonics function obtains new rotor core, because only having, the Gas-gap Magnetic Field Resonance Wave producing between rotor core and stator core added triple-frequency harmonics, but do not exist for its tertiary current of Y-connection winding, thereby under the prerequisite of torque pulsation that does not increase motor, increase torque output, and made to adopt the built-in permanent magnetic motor of this rotor core shape to there is the advantages such as power density is high, high effect Jie Neng ﹑ running is level and smooth, noise is low.

Accompanying drawing explanation

Fig. 1 is one of conventional rotors core structure schematic diagram of the prior art.

Fig. 2 is two of conventional rotors core structure schematic diagram of the prior art.

Fig. 3 is the motor general assembly drawing of the embodiment of the present invention.

Fig. 4 is the rotor core structure schematic diagram shown in Fig. 3.

Fig. 5 is the schematic diagram that the motor gas-gap length of the embodiment of the present invention changes with rotor-position.

The rotor core contour structure schematic diagram that the syllogic processing method of Fig. 6 embodiment of the present invention realizes.

Fig. 7 is the comparison diagram that the motor of the present embodiment and the cogging torque of prior art motor change with rotor-position.

Fig. 8 is the comparison diagram that the motor of the present embodiment and the torque of prior art motor change with rotor-position.

Embodiment

Under by reference to the accompanying drawings embodiment the present invention is described in further detail.

As shown in Fig. 3～Fig. 8, the present embodiment relates to the rotor core that a kind of built-in permanent magnetic motor is used, and is illustrated in figure 3 the general assembly drawing of this motor, and motor is comprised of motor stator 1 and rotor core 2, and permanent magnet 3 is circumferentially embedded on this rotor along rotor core 2.

The distribution of air-gap field during machine operation and the performance of motor have closely related, the gas length of tradition embedded actuator changes as shown in Figure 1 with rotor-position, the permanent magnet 3 ' of embedded actuator is embedded on rotor core 2 ', between motor stator 1 ' and rotor core 2 ', form air gap 4 ', the magnetic field harmonic content of the square-wave profile producing during this machine operation is high, thereby causes the cogging torque of motor large with the pulsation of operation torque; Air gap 4 shown in Fig. 2 " length adopted anticosine wavelength-division cloth, although its amplitude size is identical with square wave field, fundamental voltage amplitude has reduced, thereby has reduced the torque density of motor, has reduced overall efficiency.

The present embodiment, to there being air gap 4 length that form between motor stator 1 and rotor core 2 to adopt the stack of anticosine ripple and triple-frequency harmonics, obtains the rotor core outer rim with novel curved surface profile shape.

The outer rim of the rotor core 2 of corresponding each permanent magnet 3 of the present embodiment includes basal surface and upper end face; Wherein, the surface of basal surface and built-in permanent magnetic body 3 fits; The iron core of upper end face and motor stator 1 is relative and establish and form air gap 4, on this, the outline line of end face and air gap 4 intersections is the curve that anticosine ripple and triple-frequency harmonics function are formed by stacking, and the function that the concrete shape of this curve is represented by following formula (I) is determined:

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-a\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(I\right)$

Above-mentioned formula (I) adopts polar coordinate system, wherein, and the L in above-mentioned formula (1) _g(θ) be described air gap 4 with the outline line of the upper end face intersection of rotor core 2 iron cores on the utmost point footpath of any point M, θ be described air gap 4 with the outline line of the upper end face intersection of rotor core 2 iron cores on the polar angle of any point M; τ _pfor pole span; A is for injecting the amplitude of triple-frequency harmonics; L _gfor minimal air gap distance; L _gdfor pole span.

When setting a=1/6, the output torque maximum of motor now, obtains the function of following formula, and curve shape is referring to Fig. 5:

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-\frac{1}{6}\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(\mathrm{II}\right)$

Because above-mentioned curve is the outline line of the upper end face intersection of air gap 4 and rotor core 2 iron cores, be that the curve of gas length and the outer contour of rotor core are identical, according to above-mentioned curve, can process the shape of the electronics rotor core of the magnetic field requirement that meets built-in permanent magnetic motor.

But the rotor core 2 obtaining shown in Fig. 5 needs during fabrication to add optimum triple-frequency harmonics function by an anticosine and realizes, its course of processing is complicated, and manufacturing cost is high.In order to simplify manufacture process, the present embodiment has also proposed a kind of rotor core method for designing that can simplify and substitute the processing method of above-mentioned rotor core, and referring to Fig. 6, this method for designing includes following steps:

(1), set the amplitude a=1/6 of described triple-frequency harmonics function, the upper end face curve shape of described rotor core is by the function representation of following formula (II):

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-\frac{1}{6}\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(\mathrm{II}\right)$

(2), curve that function in described formula (II) is formed substitutes by three sections of camber lines that connect successively, described three sections of camber lines are respectively left half arc, top arc and right half arc, wherein left half arc and right half arc are for being symmetrical arranged;

(3), set the curve peak L that the function in described formula (II) forms _g(θ) _maxthe point tangent with the horizontal line that represents motor gas-gap is P1, sets the curve minimum point L that the function in described formula (II) forms _g(θ) _minfor P2;

(4), described top arc is radius and through the drawn circular arc of described some P1, some P2, determines respectively by take the maximum radius of described rotor core;

(5), described left half arc is by determining through described some P1, P2 and with the tangent circular arc of the horizontal line of described motor gas-gap respectively, described right half arc is symmetrical arranged with described left half arc and arc radius equates;

(6), described left half arc, top arc be connected successively with right half arc, formed camber line is the upper end face contour curve of described rotor core.

Can see, its contour curve of the rotor core that above-mentioned method for designing obtains is formed by connecting by three sections of circular arcs, and the recessed a little and structure of two ends projection in the middle of being by the rotor core actual curve shape that formula (II) obtains, the amplitude recessed due to centre is very little, in the actual course of processing, middle lower concave part can be similar to by take the circularity substitution that rotor core maximum radius is radius, the curve of both sides is also determined by the mode of step (3) and step (5) by left half arc and right half arc respectively, this has just simplified the course of processing greatly, has reduced difficulty of processing.

Figure 7 shows that the cogging torque comparison diagram of the embedded actuator of different rotor core outer rim shapes, the electromagnetic torque comparison diagram of the embedded actuator that Figure 8 shows that different rotor core shapes in nominal load situation; As can be seen from the figure, with respect to traditional built-in permanent magnetic motor, can torque ripple reduction by add the rotor core outer rim of triple-frequency harmonics functional based method design by anticosine, compare the magneto that anticosine is cut the utmost point, its average torque output has improved 11.5%, and torque pulsation does not increase.

On the other hand, the syllogic designed arc-shaped appearance method that the present embodiment adopts obtains rotor core not only can reduce the difficulty of processing of rotor core, and its average torque delivery efficiency with by the anticosine of standard, cut the utmost point and triple-frequency harmonics and cut rotor core that utmost point stack design obtains and also compare and increase, and torque pulsation does not increase, therefore with cutting the utmost point and triple-frequency harmonics by anticosine in syllogic designed arc-shaped appearance method place of equation (II), to cut the permanent magnet that method for designing that the utmost point superposes processes the present embodiment be feasible, is also a kind of more practical and efficient method.

Claims (3)

1. the rotor core that built-in permanent magnetic motor is used, described rotor core is embedded with a plurality of permanent magnets along circumferentially uniform, it is characterized in that: the outer rim of the described rotor core of corresponding each permanent magnet includes

Basal surface, the surface of this basal surface and built-in permanent magnetic body fits;

Upper end face, on this, the stator core of end face and described motor is relative and establish and form air gap, the outline line of the upper end face intersection of described air gap and described rotor core is the curve that anticosine ripple and triple-frequency harmonics function are formed by stacking, and the function that the concrete shape of this curve is represented by following formula (I) is determined:

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-a\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(I\right)$

Above-mentioned formula (I) adopts polar coordinate system, wherein, and the L in above-mentioned formula (1) _g(θ) be the utmost point footpath of any point M on the outline line of upper end face intersection of described air gap and rotor core, θ is the polar angle of any point M on the outline line of upper end face intersection of described air gap and rotor core; τ _pfor pole span; A is for injecting the amplitude of triple-frequency harmonics; L _gfor minimal air gap distance; L _gdfor pole span.

2. the rotor core method for designing that built-in permanent magnetic motor as claimed in claim 1 is used, is characterized in that: described method for designing includes following steps:

(1), set the amplitude a=1/6 of described triple-frequency harmonics function, the upper end face curve shape of described rotor core is by the function representation of following formula (II):

$L_g\left(\mathrm{\&theta;}\right)=\frac{\sqrt{3}{L}_{\mathrm{gd}}}{2(\cos \left(\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right)-\frac{1}{6}\cos \left(3\frac{\mathrm{\&pi;}}{{\mathrm{\&tau;}}_p}\mathrm{\&theta;}\right))}---\left(\mathrm{II}\right)$

(2), curve that function in described formula (II) is formed substitutes by three sections of camber lines that connect successively, described three sections of camber lines are respectively left half arc, top arc and right half arc, wherein left half arc and right half arc are for being symmetrical arranged;

(3), set the curve peak L that the function in described formula (II) forms _g(θ) _maxthe point tangent with the horizontal line that represents motor gas-gap is P1, sets the curve minimum point L that the function in described formula (II) forms _g(θ) _minfor P2;

(4), described top arc is radius and through the drawn circular arc of described some P1, some P2, determines respectively by take the maximum radius of described rotor core;

(5), described left half arc is by determining through described some P1, P2 and with the tangent circular arc of the horizontal line of described motor gas-gap respectively, described right half arc is symmetrical arranged with described left half arc and arc radius equates;

(6), described left half arc, top arc be connected successively with right half arc, formed camber line is the upper end face contour curve of described rotor core.

3. rotor core method for designing according to claim 3, is characterized in that: between described left half arc, top arc and right half arc, be smooth transition connection.